1. Field of the Invention
This invention relates to systems and methods for rearranging data records in accordance with the value of a keyfield associated with each record.
Information to be processed by a computer apparatus may be stored in computer memory or on some external storage device such as a magnetic tape or magnetic disk. The information is typically blocked or grouped into units, commonly referred to as "records" each of which contains similar information. For example, a business may compile a record on each of its employees, customers and/or products. Each record is comprised of different pieces of information, commonly referred to as "fields." For example, an employee record may include fields such as his name, age, address and social security number. Each field contains one or more alphanumeric characters. Each alphanumeric character is typically coded in binary form.
It is frequently desirable to arrange or rearrange records into an ordered sequence under the control of a selected field, commonly referred to as the "keyfield." For example, it may be desirable to arrange employee records in alphabetical order by employee name. This is typically accomplished by viewing the code for the alphanumeric characters comprising the keyfield as a binary number and then forming an ordered sequence under the control of that binary number.
2. Description of the Prior Art
Rearranging records is one of the most extensive computations performed by today's general purpose computers. To accomplish this task, systems for rearranging records in accordance with the coded binary value of a keyfield associated with each record are well known. However, such systems have several disadvantages associated with them. For example, some systems operate at relatively slow speeds due to the fact that for each record, each and every bit comprising the keyfield of that record is processed in series. Other systems also function at relatively slow speeds due to the fact that the keyfield of a record is directly compared with the keyfields of many or all other records. Some systems overcome this speed limitation, but require multiple, duplicative stages of comparison hardware and/or relatively large amounts of local storage
Accordingly, it is an object of the present invention to provide a general system and method for rearranging a plurality of records in accordance with the coded binary value of a keyfield associated with each record which overcomes the above disadvantages.